If you are 16 or 17, you can only register to vote, BUT you are not allowed to vote until you are 18.

Please see the attachment below giving a full list of Commonwealth and European Union countries. If you are a citizen of one of these countries, and resident in the UK, you are eligible to register to vote in UK elections. To qualify, Commonwealth citizens must be resident in the UK and either have leave to remain in the UK or not require such leave. The definition of a Commonwealth citizen includes citizens of British Crown Dependencies and British Overseas Territories.

Citizens of the European Union, who are not Commonwealth citizens, can vote in European and Local Elections in the UK, but are not able to vote in UK Parliamentary general elections.